Method and apparatus for management of extended mobile device identity information

ABSTRACT

A method of operating a terminal device to establish a radio resource control connection with network infrastructure equipment in a wireless telecommunications network, wherein the terminal device is associated with a previously-allocated temporary identifier that identifies the terminal device within the wireless telecommunications network; the method comprising: transmitting a first message to the network infrastructure equipment comprising an indication of a first portion of the temporary identifier; and transmitting a second message, which is separate from the first message, to the network infrastructure equipment comprising an indication of a second portion of the temporary identifier.

BACKGROUND Field

The present disclosure relates to telecommunications apparatus andmethods.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Recent generation mobile telecommunication systems, such as those basedon the 3GPP defined UMTS and Long Term Evolution (LTE) architectures,are able to support a wider range of services than simple voice andmessaging services offered by previous generations of mobiletelecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data-rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. In addition to supportingthese kinds of more sophisticated services and devices, it is alsoproposed for newer generation mobile telecommunication systems tosupport less complex services and devices which make use of the reliableand wide ranging coverage of newer generation mobile telecommunicationsystems without necessarily needing to rely on the high data ratesavailable in such systems.

Future wireless communications networks will therefore be expected toroutinely and efficiently support communications with a wider range ofdevices associated with a wider range of data traffic profiles and typesthan current systems are optimised to support. For example it isexpected that future wireless communications networks will efficientlysupport communications with devices including reduced complexitydevices, machine type communication (MTC) devices, high resolution videodisplays, virtual reality headsets and so on. Some of these differenttypes of devices may be deployed in very large numbers, for example lowcomplexity devices for supporting the “Internet of Things”, and maytypically be associated with the transmission of relatively smallamounts of data with relatively high latency tolerance.

In view of this there is expected to be a desire for future wirelesscommunications networks, for example those which may be referred to as5G or new radio (NR) system/new radio access technology (RAT) systems,as well as future iterations/releases of existing systems, toefficiently support connectivity for a wide range of devices associatedwith different applications and different characteristic data trafficprofiles.

One example area of current interest in this regard includes theso-called “Internet of Things”, or IoT for short. The 3GPP has proposedin Release 13 of the 3GPP specifications to develop technologies forsupporting narrowband (NB)-IoT and so-called enhanced MTC (eMTC)operation using a LTE/4G wireless access interface and wirelessinfrastructure. More recently there have been proposals to build onthese ideas in Release 14 of the 3GPP specifications with so-calledenhanced NB-IoT (eNB-IoT) and further enhanced MTC (feMTC), and inRelease 15 of the 3GPP specifications with so-called further enhancedNB-IoT (feNB-IoT) and even further enhanced MTC (efeMTC). See, forexample, [1], [2], [3], [4]. At least some devices making use of thesetechnologies are expected to be low complexity and inexpensive devicesrequiring relatively infrequent communication of relatively lowbandwidth data. It is further expected some of these types of device maybe required to operate in areas of relatively poor coverage, forexample, in a basement or other location with relatively highpenetration loss (e.g. for smart meter type applications), or in remotelocations (e.g. for remote monitoring applications), and this has givenrise to proposals for enhancing coverage, for example using repeattransmissions.

The increasing use of different types of terminal devices associatedwith different traffic profiles and requirements for coverageenhancement gives rise to new challenges for efficiently handlingcommunications in wireless telecommunications systems that need to beaddressed.

SUMMARY

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 schematically represents some aspects of a LTE-type wirelesstelecommunication system which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 2 schematically represents steps in a random access procedure in awireless telecommunication network;

FIG. 3 schematically represents some aspects of a wirelesstelecommunication system in accordance with certain embodiments of thepresent disclosure;

FIG. 4 schematically represents some aspects of a 5G-type wirelesstelecommunication system which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 5 is a message sequence chart representing a sequence oftransmissions which may be carried out in accordance with certainembodiments of the present disclosure;

FIG. 6 illustrates a temporary identity and the contents of messagesformed in accordance with certain embodiments of the present disclosure;

FIG. 7 illustrates messages, their contents and a look-up table inaccordance with certain embodiments of the present disclosure;

FIG. 8A illustrates a message sequence chart representing a sequence oftransmissions for establishing a protocol data unit, PDU, session inaccordance with embodiments of the present disclosure;

FIG. 8B illustrates a look-up table in accordance with certainembodiments of the present disclosure;

FIG. 8C illustrates the contents of a message in accordance with certainembodiments of the present disclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system 100operating generally in accordance with LTE principles, but which mayalso support other radio access technologies, and which may be adaptedto implement embodiments of the disclosure as described herein. Variouselements of FIG. 1 and certain aspects of their respective modes ofoperation are well-known and defined in the relevant standardsadministered by the 3GPP (RTM) body, and also described in many books onthe subject, for example, Holma H. and Toskala A [5]. It will beappreciated that operational aspects of the telecommunications networksdiscussed herein which are not specifically described (for example inrelation to specific communication protocols and physical channels forcommunicating between different elements) may be implemented inaccordance with any known techniques, for example according to therelevant standards and known proposed modifications and additions to therelevant standards.

The network 100 includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from terminal devices104. Data is transmitted from base stations 101 to terminal devices 104within their respective coverage areas 103 via a radio downlink Data istransmitted from terminal devices 104 to the base stations 101 via aradio uplink The core network 102 routes data to and from the terminaldevices 104 via the respective base stations 101 and provides functionssuch as authentication, mobility management, charging and so on.Terminal devices may also be referred to as mobile stations, userequipment (UE), user terminals, mobile radios, communications devices,and so forth. Base stations, which are an example of networkinfrastructure equipment/network access nodes, may also be referred toas transceiver stations/nodeBs/e-nodeBs, g-nodeBs and so forth. In thisregard different terminology is often associated with differentgenerations of wireless telecommunications systems for elementsproviding broadly comparable functionality. However, certain embodimentsof the disclosure may be equally implemented in different generations ofwireless telecommunications systems, and for simplicity certainterminology may be used regardless of the underlying networkarchitecture. That is to say, the use of a specific term in relation tocertain example implementations is not intended to indicate theseimplementations are limited to a certain generation of network that maybe most associated with that particular terminology.

While certain embodiments may be generally described herein in relationto the network architecture represented in FIG. 1, it will beappreciated corresponding approaches may equally be adopted in networksconforming to other overall configurations, for example configurationsassociated with proposed approaches for new radio access technology(RAT), NR, wireless mobile telecommunications networks/systems. A newRAT network may comprise communication cells that each comprise acontrolling node in communication with a core network component and aplurality of distributed units (radio access nodes/remote transmissionand reception points (TRPs)) within the cell. The distributed units maybe responsible for providing the radio access interface for terminaldevices connected to the NR network. Each distributed unit has acoverage area (radio access footprint) which together define thecoverage of the communication cell. Each distributed unit includestransceiver circuitry for transmission and reception of wireless signalsand processor circuitry configured to control the respective distributedunits. In terms of broad top-level functionality, the core networkcomponent of such a new RAT telecommunications system may be broadlyconsidered to correspond with the core network 102 represented in FIG.1, and the respective controlling nodes and their associated distributedunits/TRPs may be broadly considered to provide functionalitycorresponding to base stations of FIG. 1. Thus, the term networkinfrastructure equipment/access node may be used to encompass theseelements and more conventional base station type elements of wirelesstelecommunications systems. Depending on the application at hand theresponsibility for scheduling transmissions which are scheduled on theradio interface between the respective distributed units and theterminal devices may lie with the controlling node/centralised unitand/or the distributed units/TRPs. A terminal device operating in thisproposed new RAT architecture may thus exchange signalling with a firstcontrolling node via one or more of the distributed units associatedwith the controlling node. In some implementations the involvement ofthe distributed units in routing communications from the terminal deviceto a controlling node (controlling unit) may be transparent to theterminal device. It will further be appreciated that this examplerepresents merely one example of a proposed architecture for a new RATtelecommunications system in which approaches in accordance with theprinciples described herein may be adopted, and the functionalitydisclosed herein may also be applied in respect of wirelesstelecommunications systems having different architectures.

Thus certain embodiments of the disclosure as discussed herein may beimplemented in wireless telecommunication systems/networks according tovarious different architectures, such as the example architecture shownin FIG. 1. It will be appreciated that the specific wirelesstelecommunications architecture in any given implementation is not ofprimary significance to the principles described herein. In this regard,certain embodiments of the disclosure may be described generally in thecontext of communications between network infrastructureequipment/access nodes and a terminal device, wherein the specificnature of the network infrastructure equipment/access node and theterminal device will depend on the network infrastructure for theimplementation at hand. For example, in some scenarios the networkinfrastructure equipment/access node may comprise a base station, suchas an LTE-type base station 101 as shown in FIG. 1 which is adapted toprovide functionality in accordance with the principles describedherein, and in other examples the network infrastructure equipment maycomprise a control unit/controlling node and/or a TRP in a new RATarchitecture of the kind discussed above.

In wireless telecommunications networks, such as LTE type networks,there are different Radio Resource Control (RRC) modes for terminaldevices. For example, it is common to support an RRC idle mode(RRC_IDLE) and an RRC connected mode (RRC_CONNECTED). A terminal devicein the idle mode may transition to connected mode, for example becauseit needs to transmit uplink data or respond to a paging request, byundertaking a random access procedure. The random access procedureinvolves the terminal device transmitting a preamble on a physicalrandom access channel and so the procedure is commonly referred to as aRACH or PRACH procedure/process.

Thus a conventional way for a terminal device (UE) in RRC idle mode toexchange data with a network involves the terminal device firstperforming an RRC connection procedure (random access procedure) withthe network. The RRC connection procedure involves the UE initiallytransmitting a random access request message (which may be triggeredautonomously by the UE determining it has data to transmit to thenetwork or in response to the network instructing the UE to connect tothe network). This is followed by RRC control message exchange betweenthe network and UE. After establishing an RRC connection and exchangingthe relevant data, the UE may then perform RRC disconnection and moveback into idle mode for power saving. This conventional approach may forconvenience be referred to herein as a legacy approach.

FIG. 2 is a ladder diagram that schematically shows message exchangebetween a UE and an eNB in a typical random access procedure toestablish an RRC connection, in this example in an LTE-based network.The UE starts the process in step S1 by transmitting a random accessrequest on a physical random access channel (PRACH in an LTE context),i.e. a random access preamble (RACH preamble), to the eNB. In step S2,when the eNB detects this preamble it will respond with a Random AccessResponse message (RAR), which is also known as Message 2. The RAR isscheduled by DCI (downlink control information) carried on a physicaldownlink control channel, e.g. MPDCCH in an LTE implementation formachine type communication (MTC) traffic, in a predefined Common SearchSpace (CSS). The RAR itself is transmitted on a physical downlink sharedchannel (PDSCH) resource allocated via the DCI. The DCI is addressed toan RA-RNTI (random access radio network temporary identifier) which isderived from the time and frequency resources used to transmit thepreamble in step S1 and the RAR will indicate which preamble the eNB hasdetected and is responding to. It may be noted it is possible thatmultiple UEs may transmit a random access request using the same PRACHpreamble and the same time and frequency resources. The RAR of step S2also contains an uplink grant for the preamble the network is respondingto so that the UE that transmitted the preamble may use this uplinkgrant to transmit an RRC Connection Request message, also known asMessage 3 to the eNB, in step S3. Message 3 also contains an indicationof an identifier for the UE (e.g. a C-RNTI (cell radio network temporaryidentifier) or TMSI (temporary mobile subscriber identity) or a 40-bitrandom number generated by the UE. The eNB will respond to Message 3, instep S4, with Message 4 which carries a RRC Connection Setup message.For the case where multiple UEs use the same preamble, the combinationof Message 3 and Message 4 provides contention resolution functionality,for example using a terminal device identifier, such as C-RNTI or TMSI,transmitted in Message 3: when a UE receives a Message 4 that contains aportion of the Message 3 containing the temporary identity that ittransmitted earlier, it knows that there was no contention on theMessage 3 that it had transmitted. The RRC connection is establishedwhen the UE transmits Message 5 in step S5 containing a RRC ConnectionSetup Complete message.

In order to increase the number of terminal devices which areidentifiable within a wireless telecommunications network, particularlyin 5G networks, it has been proposed to increase the length of the TMSI,for example, from 40 to 48 bits. The inventors of the present techniquehave appreciated that including the longer TMSI within the message 3 atstep S3 as described above may not be feasible, without compromising thereliability or cell coverage that can be achieved using a conventionalTMSI.

In order to overcome the above problem, in embodiments of the presenttechnique, only a portion (i.e. less than all) of the TMSI is includedor indicated in the message 3. Additional information indicating theremainder of the TMSI (i.e. that portion not sent in message 3) istransmitted in message 5.

FIG. 3 schematically shows a telecommunications system 500 according toan embodiment of the present disclosure. The telecommunications system500 in this example is based broadly around an LTE-type architecture. Assuch many aspects of the operation of the telecommunicationssystem/network 500 are known and understood and are not described herein detail in the interest of brevity. Operational aspects of thetelecommunications system 500 which are not specifically describedherein may be implemented in accordance with any known techniques, forexample according to the current LTE-standards.

The telecommunications system 500 comprises a core network part (evolvedpacket core) 502 coupled to a radio network part. The radio network partcomprises a base station (evolved-nodeB) 504 coupled to a plurality ofterminal devices. In this example, two terminal devices are shown,namely a first terminal device 506 and a second terminal device 508. Itwill of course be appreciated that in practice the radio network partmay comprise a plurality of base stations serving a larger number ofterminal devices across various communication cells. However, only asingle base station and two terminal devices are shown in FIG. 3 in theinterests of simplicity.

As with a conventional mobile radio network, the terminal devices 506,508 are arranged to communicate data to and from the base station(transceiver station) 504. The base station is in turn communicativelyconnected to a serving gateway, S-GW, (not shown) in the core networkpart which is arranged to perform routing and management of mobilecommunications services to the terminal devices in thetelecommunications system 500 via the base station 504. In order tomaintain mobility management and connectivity, the core network part 502also includes a mobility management entity (not shown) which manages theenhanced packet service (EPS) connections with the terminal devices 506,508 operating in the communications system based on subscriberinformation stored in a home subscriber server (HSS). Other networkcomponents in the core network (also not shown for simplicity) include apolicy charging and resource function (PCRF) and a packet data networkgateway (PDN-GW) which provides a connection from the core network part502 to an external packet data network, for example the Internet. Asnoted above, the operation of the various elements of the communicationssystem 500 shown in FIG. 3 may be broadly conventional apart from wheremodified to provide functionality in accordance with embodiments of thepresent disclosure as discussed herein.

The terminal devices 506, 508 comprise transceiver circuitry 506 a, 508a (which may also be referred to as a transceiver/transceiver unit) fortransmission and reception of wireless signals and processor circuitry506 b, 508 b (which may also be referred to as a processor/processorunit) configured to control the devices 506, 508. The processorcircuitry 506 b, 508 b may comprise various sub-units/sub-circuits forproviding functionality as explained further herein. These sub-units maybe implemented as discrete hardware elements or as appropriatelyconfigured functions of the processor circuitry. Thus the processorcircuitry 506 b, 508 b may comprise circuitry which is suitablyconfigured/programmed to provide the desired functionality usingconventional programming/configuration techniques for equipment inwireless telecommunications systems. The transceiver circuitry 506 a,508 a and the processor circuitry 506 b, 508 b are schematically shownin FIG. 3 as separate elements for ease of representation. However, itwill be appreciated that the functionality of these circuitry elementscan be provided in various different ways, for example using one or moresuitably programmed programmable computer(s), or one or more suitablyconfigured application-specific integratedcircuit(s)/circuitry/chip(s)/chipset(s). As will be appreciated theterminal devices 506, 508 will in general comprise various otherelements associated with its operating functionality, for example apower source, user interface, and so forth, but these are not shown inFIG. 3 in the interests of simplicity.

The base station 504 comprises transceiver circuitry 504 a (which mayalso be referred to as a transceiver / transceiver unit) fortransmission and reception of wireless signals and processor circuitry504 b (which may also be referred to as a processor/processor unit)configured to control the base station 504 to operate in accordance withembodiments of the present disclosure as described herein. The processorcircuitry 504 b may comprise various sub-units/sub-circuits forproviding desired functionality as explained further herein. Thesesub-units may be implemented as discrete hardware elements or asappropriately configured functions of the processor circuitry. Thus theprocessor circuitry 504 b may comprise circuitry which is suitablyconfigured/programmed to provide the desired functionality describedherein using conventional programming/configuration techniques forequipment in wireless telecommunications systems. The transceivercircuitry 504 a and the processor circuitry 504 b are schematicallyshown in FIG. 3 as separate elements for ease of representation.However, it will be appreciated that the functionality of thesecircuitry elements can be provided in various different ways, forexample using one or more suitably programmed programmable computer(s),or one or more suitably configured application-specific integratedcircuit(s)/circuitry/chip(s)/chipset(s). It will be appreciated the basestation 504 will in general comprise various other elements associatedwith its operating functionality.

Thus, the base station 504 is configured to communicate data with theterminal devices 506, 508 according to an embodiment of the disclosureover respective communication links 510, 512. The base station 504 isconfigured to communicate with the terminal device 506 over theassociated radio communication link 510 and with the terminal device 508over the associated radio communication link 512 generally following theestablished principles of LTE-based of 5G/NR communications, apart fromusing modified procedures in accordance with certain embodiments of thepresent disclosure as described herein.

In order to improve the flexibility and range of services that can beprovided in a 5G network and to provide greater flexibility in terms ofcommercial relationships between network operators and customers, it hasbeen proposed that a wireless telecommunication system may be logicallydivided into one or more network slices. This is illustrated in FIG. 4.

The core network 102 in FIG. 4 comprises two slices, a first slice 402and a second slice 404. Each of the first and second network slices 402,404 may include a respect access and mobility management function (AMF).For example, the first network slice 402 may include a first AMF 406 andthe second network slice 404 may include a second AMF 408. The multiplenetwork slices may each be connected to the radio access network such asthe base station 101.

Within the radio access network, network slicing may be realised bymeans of resource partitioning or logical separation of communicationsresources such that each of the network slices 402, 404 havecorresponding communications resources for use by the communicationterminal 104 depending on the network slice with which it iscommunicating.

In order to facilitate the introduction of network slice functionality,each network slice is identified by network slice selection assistanceinformation, NSSAI. A terminal device, such as the terminal device 104may be configured to operate with, or subscribed to, one or more of thenetwork slices provided by a wireless telecommunication system. Anetwork slice to which a terminal device is subscribed may be identifiedby a single NSSAI (S-NSSAI). For example, in the wirelesstelecommunication system illustrated in FIG. 4, the terminal device 104may be configured to access both the first network slice 402 and thesecond network slice 404. A given protocol data unit, PDU, session isassociated with a single network slice. However, a terminal device suchas the terminal device 104 may have simultaneous PDU sessionsestablished with multiple network slices.

The S-NSSAI may comprise two portions: a slice service/type, SST, whichindicates the features or services available from a given network slice,and a slice differentiator, SD, which differentiates among multiplenetwork slices having the same slice/service type.

In the example wireless telecommunication of FIG. 4 each of the firstand second network slices 402, 404 are shown to have their ownassociated AMF, 406, 408 respectively. However in some networktypologies an AMF may be shared by multiple network slices.

A terminal device (such as the terminal device 104) may be configured toassociate certain applications running on a processor of the terminaldevice with a particular network slice, or with a particular networkslice service and/or type.

In order to accommodate the introduction of network slice functionality,it has been proposed that the message 5, which is sent in step S5 ofFIG. 2, may include a list of network slice identifiers with which theterminal device is currently associated.

FIG. 5 is a message sequence chart illustrating transmissions which maybe in accordance with examples of the present technique, between aterminal device, such as the terminal device 104, a base station oreNodeB, such as the base station 101, and an AMF, such as the AMF 406 ofFIG. 4. For clarity the terminal device 104 is shown as comprising anon-access stratum (NAS) protocol entity, 520 and an access stratum (AS)entity, 522. This distinction is shown merely for clarity and theexample embodiments described here are not limited to such a terminaldevice implementation.

The message exchange starts at step 5504 which represents an attachprocedure between the terminal device 104 and the AMF 406. The detailsof the attach procedure may be in accordance with a conventional processfor attaching with a core network. As part of the attach procedure 5504,a temporary identifier, which may be the temporary identity 600, isallocated by the AMF 406 to the terminal device 104. This may be forexample a temporary mobile subscriber identity (TMSI) and morespecifically, in the case where the AMF is in a 5G core network, thismay be a 5G-S-TMSI. In the case where the core network is an enhancedpacket core (EPC) network, the temporary identity 600 may be a systemarchitecture evolution (SAE) TMSI, S-TMSI. The temporary identity 600may be 40 bits in length or, in some embodiments of the presenttechnique, may be 48 bits long or longer. The use of a temporaryidentifier having a greater length (such as 48 bits) may permit a muchgreater number of core network entities or a greater density of terminaldevices, and/or accommodate a large number of network slices within awireless telecommunications network.

The temporary identity 600 may comprise one or more portions whichtogether identify an entity with the core network 102. For example, thetemporary identity 600 may comprise an AMF Set ID and an AMF

Pointer which together identify an AMF, such as the AMF 406, within thecore network 102. The temporary identity 600 may further comprise anidentifier (which may be, for example, a 5G-TMSI) which uniquelyidentifies the terminal device 104 amongst all terminal devicesassociated with the core network entity, such as the AMF 406.

Subsequently at step 5508 the NAS entity 520 of the terminal device 104sends a service request 606 to the access stratum (AS) entity 522 of theterminal device 104. For example the service request 606 may be inresponse to a user-initiated interaction with the terminal device 104such as requesting an internet connection or initiating a voice call.The service request 606 may be provided to the access stratum 522together with the temporary identity 600.

In response to receiving the service request 5508, the access stratum522 initiates an RRC connection establishment procedure. The RRCconnection establishment procedure may follow steps S1, S2, S3, S4, S5as illustrated in FIG. 2 and described above.

The RRC Connection request (message 3, sent at step S3) may have apredetermined size, or may have a predetermined maximum size. In FIG. 5,it is shown that, in accordance with conventional techniques, the entiretemporary identity 600 may be included in the message 3. However, insome embodiments of the present technique, as will be described below ingreater detail, only a portion of the temporary identity 600 may beincluded in the message 3. This may be because the maximum size of themessage 3 is not sufficient to allow for the inclusion of the entiretemporary identity 600. In some embodiments, the length of the message 3is predetermined, and the size of the portion of the temporary identitywhich is indicated in the message 3 is accordingly predetermined.

In some embodiments of the present technique, however, the terminaldevice 104 determines a size of the portion of the temporary identity600 to include in the message 3, based on a determination of the size ofthe message 3.

According to conventional techniques, then, because the terminal device104 has been allocated the temporary identity 600 by the AMF 406, thetemporary identity 600 is included in the message 3 at step

S3 as described above and is therefore used in the contention resolutionprocedure. That is, in order to identify which terminal device the basestation 101 is establishing a connection with, the message S3 includesthe temporary identity 600 which is subsequently included in the RRCconnection setup message, S4, transmitted by the base station 101. Thisavoids any confusion by the terminal device 104 as to whether or not thebase station 101 is responding to its message 3 or to that of anotherterminal device which may have transmitted a message identical to theRRC connection request message S1 at the same time as the transmissionof the RRC connection request message S1.

As described above, in some embodiments of the present technique, anindication of a first portion of the temporary identity 600 is includedin the message 3 at step S3. As such, no indication of the completetemporary identity 600 is included in the message 3. The contentionresolution process may therefore, in some embodiments, be based on theuse of some or all of the portion of the temporary identity 600 which isincluded in the message 3.

After the contention resolution procedure is complete, the terminaldevice 104 at step S5 transmits in the message 5 the service request 606which was received in step S508 from the NAS entity 520 by the accessstratum entity 522. In a wireless telecommunications network havingmultiple network slices, the message 5 may further comprise sliceidentity information.

According to some embodiments of the present technique, the message 5may comprise an indication of a second portion of the temporary identity600. In some embodiments of the present technique, the length of themessage 5 is not predetermined.

As described above, the temporary identity 600 which was issued by theAMF 406 in the attach procedure may comprise an indication of theidentity of the AMF 406. As such, or based on any suitablepre-configuration, the base station 101, having received the temporaryidentity 600 at step S3 may, according to conventional techniques,identify the AMF 406 to which the terminal device 104 is attempting totransmit the service request 606. In response to receiving the message 5at step S5 the base station 101 is thus able to identify the AMF 406 andtherefore to transmit the service request to the AMF 406 at step S510.

From the above description it will be apparent that the temporaryidentity 600 allocated by the AMF 406 may in fact have multiplepurposes. Specifically, the temporary identity 600 may first identifythe terminal device 104 within the wireless telecommunications networkthereby permitting subsequent paging or connection establishment withthe terminal device 104.

In addition, the temporary identity 600 provides a means for thecontention resolution procedure, comprising steps S3 and S4. Finally thetemporary identity 600, comprising a portion which permits the basestation 101 to identify an AMF within the core network 102, enables thebase station 101 to route the service request to the appropriate AMF asillustrated in step S510 above.

The inventors of the present technique have recognised, inter alia,that, in accordance with embodiments of the present technique describedherein, two or more of these different requirements can be satisfiedwhile meeting a constraint on the length of the message 3 transmitted atstep S3, which may prevent the entire temporary identity 600 beingincluded in the message 3.

In accordance with example embodiments of the present technique, thesequence of messages represented in FIG. 5 may be adapted, as will bedescribed below. However, it will be readily apparent that thetechniques described herein are not limited to the scenario illustratedin FIG. 5.

For example, although in the message sequence of FIG. 5 the servicerequest 606 is sent from the NAS 520 to the AS 522, the techniquesdisclosed herein are not so limited, and may be applied as a result of arequest of a different nature sent from the NAS 520 to the AS 522, ormay be carried out autonomously by the AS 522, absent any request fromthe NAS 520. In some embodiments of the present technique, includingthose in which no NAS-originated message is to be transmitted to thecore network 102, step s510 may be omitted.

Some example embodiments of the present technique thus provide a meansfor a base station 101 to derive a temporary identity 600 of a terminaldevice 104. Some example embodiments of the present technique provide,additionally or alternatively, a means for a base station 101 to performcontention resolution using at least a portion of the temporary identity600 and to identify a core network entity to which a furthertransmission may be directed.

In particular, in some embodiments of the present technique, it is notnecessary for the base station 101 to determine the complete temporaryidentity 600 of the terminal device 104.

For example, in some embodiments, the base station 101 determines, basedon one or both of the portion of the temporary identity 600 which isincluded in the message 3, and the additional information included inthe message 5, the identity of the core network entity to which itshould transmit subsequently (e.g. in order to forward a NAS messagewhich was included in the message 5).

In some embodiments, the complete temporary identity 600 is,additionally, included within a NAS container (which may include, forexample, the service request 604) which is transmitted transparently viathe base station 101, without the base station 101 parsing or otherwisedetermining the information contained within the container. In suchcases, the base station 101 determines the identity of the core networkentity, such as the AMF 406 to which the NAS container is to betransmitted and transmits the NAS container accordingly. The corenetwork entity (such as the AMF 406) receives the NAS container anddecodes it, thereby determining the temporary identity 600 of theterminal device 104.

In other embodiments, the base station 101 determines the completetemporary identity 600 in accordance with one or more approachesdescribed herein, and may include the temporary identity 600 in themessage (such as the message 510) which is transmitted to the corenetwork. In some embodiments, the base station 101 in accordance withone or more of the approaches described herein, determines the completetemporary identity 600 and associates it with the established RRCconnection. The base station 101 may subsequently transmit the completetemporary identity 600 as part of a procedure to hand over, or otherwisefacilitate the mobility of, the terminal device 104. In someembodiments, therefore, the base station 101 may not determine theidentity of a core network entity.

In an embodiment of the present technique, the temporary identity 600comprises a user equipment (UE) ID portion 602 and an AMF ID portion604, as depicted in FIG. 6. The size of the UE ID portion 602 is suchthat it can fit within the message 3 610. According to such embodimentsof the present technique, the message 3 610 includes the UE ID portion602 of the temporary ID and thus the UE ID portion 602 may be used forthe contention resolution part of the random access procedure.

After the contention resolution procedure, the message 5 620 istransmitted from the UE 104 to the base station 101 containing the AMFID portion 604. In some embodiments of the present technique the message5 620 further includes the service request 606 which was received fromthe UE's NAS entity 520 by the UE's AS entity 522.

In some embodiments of the present technique, the AMF ID portion 604comprises one or more of an AMF set ID or an AMF region ID.

In some embodiments the temporary identity 600 comprises an indicationof a region in which the terminal device 104 is currently registered, inaddition to, or in combination with the AMF ID portion 604. For example,the indication of the region may be a tracking area identity (TAI).Accordingly, within the message 5 620, the tracking area identity may beincluded. In some embodiments, the TAI is configured according to apolicy of the operator of the wireless telecommunications system. Thebase station 101 may be configured using, for example, operation andmaintenance techniques, with a mapping between TAI and AMF ID. As such,the base station 101 may determine the AMF ID, such as the identity ofthe AMF 406, based on the TAI provided in the message 5 620.

In a further embodiment of the present technique the message 5 620comprises an indication of a network slice identifier 608. The message 3610 contains the UE ID portion 602 as before, and the message 5 620includes an indication of a network slice identifier 608. The indicationof the network slice identifier 608 may comprise an S-NSSAI, or a listof S-NSSAI's 618.

According to some embodiments of the present disclosure the networkslice indication 608 comprises a list of S-NSSAI's 618, and the S-NSSAIto be associated with the UE ID portion 602 is the one in apredetermined position, for example, the S-NSSAI 618 a in a firstposition in the list. In some embodiments of the present technique, theS-NSAIs 618 a, 618 b, 618 c in the list of S-NSSAIs 618 are orderedaccording to when the terminal device 104 was most recently connected tothe respective network slice. For example, the first S-NNSAI 618 a maycorrespond to the network slice to which the terminal device 104 wasmost recently connected, and so on.

In some embodiments of the present technique, the network sliceindication 608 in the message 5 620 may indicate the identity of a sliceto which the terminal device 104 wishes to connect (for example, theslice to which the terminal device 104 to which the base station 101 isto transmit the service request 606). As such, in some such embodiments,the network slice indication 608 in the message 5 620 may indicate theidentity of a slice which does not contain the AMF 406 from which thetemporary identity 600 was received.

In some embodiments of the present technique the base station 101 isconfigured to store an association between network slice identifiers andthe identities of an AMF entity within the corresponding slice. Forexample, the base station 101 may store in memory an AMF ID table 702 inwhich each of one or more S-NSSAIs are associated with an AMF ID.

As such, in response to receiving the message 3 610 and the message 5620 containing the indication of the network slice identifier 608, thebase station 101 derives first an S-NSSAI and, based on the configuredmapping between S-NSSAIs and AMF identities, determines the contents ofthe AMF ID portion 604. Based on the determined AMF ID portion 604 thebase station 101 transmits the service request 606 to the identified AMFfunction within the appropriate network slice. For example, the S-NSSAIin the first position 618 a of the list of NSSAI's 608 may indicate theidentity of the network slice 402 illustrated in FIG. 4. The basestation 101 may thus identify the AMF 406 based on receiving theidentity of the network slice 402 in the message 5 620.

In some embodiments of the present technique, the UE ID portion 602 maycomprise a conventional S-TMSI or 5G-S-TMSI. As such, or in any case,the UE ID portion 602 may include an indication of the identity (forexample, in the form of an AMF set ID and/or an AMF pointer) of the corenetwork entity from which the TMSI was obtained, or to which theterminal device 104 is attempting to connect or re-connect.

A further embodiment of the present technique is illustrated in FIG. 8A,FIG. 8B and FIG. 8C. FIG. 8 shows a protocol data unit, PDU sessionestablishment process 802 by which the UE 101 establishes via the basestation 101 a PDU session with the AMF 406. The PDU establishmentprocess may proceed according to a conventional approach and forclarity, not all messages within the process are shown in FIG. 8.

The PDU establishment process 802 may comprise the transmission by theUE 101 to the base station 101 of a PDU session establishment requestmessage 804. The PDU session establishment request message 804 maycomprise a PDU session ID and an identity (for example, an S-NNSAI) of anetwork slice with which the UE 101 wishes to establish a PDU session.

As part of the PDU session establishment process 802, the base station101 may thus determine an association between an identity of the UE 101,the PDU session ID and the identity of the network slice associated withthe PDU session. The base station 101 may, for example, store suchassociation in a table having the form of a PDU session table 808illustrated in FIG. 8B. In accordance with some embodiments of thepresent technique, the PDU session ID may be indicated to the basestation 101 in a manner that does not require the base station 101 todecode message contents which are generated by, or for, a non-accessstratum protocol entity. For example, the PDU session ID may be includedin the access stratum portion of the message which comprises the PDUsession establishment request message 804.

Subsequently according to embodiments of the present technique, themessage 3 610 may comprise the UE ID portion 602 of the temporaryidentity. As illustrated in FIG. 8C, the message 5 620 may comprise anindication 806 of the identity of the PDU session which was establishedin the PDU session establishment process 802. In accordance with someembodiments of the present technique, the PDU session ID may be includedin the message 5 620 in a manner that does not require the base station101 to decode message contents which are generated by, or for, anon-access stratum protocol entity. For example, the PDU session ID maybe included in the portion (which may be an access stratum portion) ofthe message 5 620 which is to be decoded by the base station 101.

In some embodiments, the message 5 620 may comprise the indication 608of the identity of the network slice with which the PDU session wasestablished in the PDU session establishment process 802. (Theindication 608 may be of a form described above in respect of FIG. 7).

For example, the indication 806 may comprise the PDU session IDindicated in the transmission 804 of the PDU session establishment 802.Based on the stored association between the identity of the UE 101, theidentity of the PDU session, and the identity of the network slice, thebase station 101 determines the identity of the network slice and, basedon a stored association between the network slice identity and theidentity of the AMF 406 (which may be, for example, in the form of theAMF ID table 702), is able to transmit the service request 606 to theAMF 406.

In some embodiments, the NAS layer 520 in the UE 104 handles a mappingbetween the PDU session ID and the order of slices whose identities areincluded in the list 618 of slice identifiers. This approach allows adynamic change of the mapping between PDU session identifier and sliceidentifier.

In other embodiments, the NAS entity 520 provides the list 618 of sliceidentifiers and the PDU session ID to the AS layer 522 of the terminaldevice 104, and the AS layer 522 performs the mapping, to generate thelist 618 of slice identifiers or the indication 608 of the identity ofthe network slice.

In other embodiments, the AS layer 522 includes an indication of the PDUsession ID in the message 5 620 and the base station 101, having storedpreviously a mapping from the PDU session ID to the identity of thenetwork slice, determines the identity of the network slice based on thePDU session ID indicated in the message 5 620.

In some embodiments, the message 5 620 may include one or both of anindication of the PDU session ID and an indication of the identity ofthe network slice, thereby providing greater flexibility and permittinga dynamic mapping between PDU session ID, network slice and AMF ID.

As described above, various approaches have been described which addressthe various problems resulting from the use of a temporary identity 600which exceeds the available capacity of the message 3 610.

According to some embodiments of the present technique, in order toprovide suitable flexibility and to accommodate various networkdeployment scenarios, the terminal device 104 may indicate, for exampleby means of an indication included in the message 5 as to which approachhas been used, or in other words, an indication of how the base station101 is to determine the complete temporary identity 600 and/or theidentity of the core network entity (such as the AMF 406) to which anysubsequent transmission by the base station 101 is to be directed.

In some embodiments of the present technique, the method by which theterminal device constructs the message 3 610 and the message 5 620 so asto enable the base station 101 to determine the complete temporaryidentity 600 and/or the identity of the core network entity, isindicated in a message transmitted by the base station 101, for examplein broadcast system information. Alternatively, such an indication maybe transmitted as part of non-access stratum signalling, for example aspart of the PDU session establishment procedure 802.

In some embodiments of the present technique, the same method is usedregardless of whether the wireless access interface provided by the basestation 101 is compliant with the LTE specifications or with the NRspecifications.

In yet some further embodiments of the present technique, a first methodis used if the wireless access interface provided by the base station101 is compliant with the LTE specifications, and a second method isused if the wireless access interface provided by the base station 101is compliant the NR specifications.

The inventors of the present disclosure further recognise that thevarious approaches described herein may permit, in some embodiments, thesize of the message 3 610 to be reduced, compared to conventionalmessage 3 formats. For example, in some embodiments, the UE ID portion602 may be only 32 bits long, and the message 3 610 may be accordinglyformatted so that only 32 bits of a temporary identity may be included.In such embodiments, various well-known techniques (for example, morerobust encoding) may be used to increase the coverage area from withinwhich the message 3 610 may be reliably received by the base station101.

Thus there has been described a method of operating a terminal device toestablish a radio resource control connection with networkinfrastructure equipment in a wireless telecommunications network,wherein the terminal device is associated with a previously-allocatedtemporary identifier that identifies the terminal device within thewireless telecommunications network; the method comprising: transmittinga first message to the network infrastructure equipment comprising anindication of a first portion of the temporary identifier; andtransmitting a second message, which is separate from the first message,to the network infrastructure equipment comprising an indication of asecond portion of the temporary identifier.

It will be appreciated that while the present disclosure has in somerespects focused on implementations in an LTE-based and/or 5G networkfor the sake of providing specific examples, the same principles can beapplied to other wireless telecommunications systems. Thus, even thoughthe terminology used herein is generally the same or similar to that ofthe LTE and 5G standards, the teachings are not limited to the presentversions of LTE and 5G and could apply equally to any appropriatearrangement not based on LTE or 5G and/or compliant with any otherfuture version of an LTE, 5G or other standard.

It may be noted various example approaches discussed herein may rely oninformation which is predetermined/predefined in the sense of beingknown by both the base station and the terminal device. It will beappreciated such predetermined/predefined information may in general beestablished, for example, by definition in an operating standard for thewireless telecommunication system, or in previously exchanged signallingbetween the base station and terminal devices, for example in systeminformation signalling, or in association with radio resource controlsetup signalling, or in information stored in a SIM application. That isto say, the specific manner in which the relevant predefined informationis established and shared between the various elements of the wirelesstelecommunications system is not of primary significance to theprinciples of operation described herein. It may further be notedvarious example approaches discussed herein rely on information which isexchanged/communicated between various elements of the wirelesstelecommunications system and it will be appreciated such communicationsmay in general be made in accordance with conventional techniques, forexample in terms of specific signalling protocols and the type ofcommunication channel used, unless the context demands otherwise. Thatis to say, the specific manner in which the relevant information isexchanged between the various elements of the wirelesstelecommunications system is not of primary significance to theprinciples of operation described herein.

It will be appreciated that the principles described herein are notapplicable only to certain types of terminal device, but can be appliedmore generally in respect of any types of terminal device, for examplethe approaches are not limited to machine type communication devices/IoTdevices or other narrowband terminal devices, but can be applied moregenerally, for example in respect of any type terminal device operatingwith a wireless link to the communication network.

It will further be appreciated that the principles described herein arenot applicable only to LTE-based wireless telecommunications systems,but are applicable for any type of wireless telecommunications systemthat supports a random access procedure comprising an exchange of randomaccess procedure messages between a terminal device and a base station.

Further particular and preferred aspects of the present invention areset out in the accompanying independent and dependent claims. It will beappreciated that features of the dependent claims may be combined withfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. As will be understood by thoseskilled in the art, the present invention may be embodied in otherspecific forms without departing from the spirit or essentialcharacteristics thereof. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting of the scopeof the invention, as well as other claims. The disclosure, including anyreadily discernible variants of the teachings herein, define, in part,the scope of the foregoing claim terminology such that no inventivesubject matter is dedicated to the public.

Respective features of the present disclosure are defined by thefollowing numbered paragraphs:

Paragraph 1. A method of operating a terminal device to establish aradio connection with network infrastructure equipment in a wirelesstelecommunications network, wherein the terminal device is associatedwith a previously-allocated temporary identifier that identifies theterminal device within the wireless telecommunications network; themethod comprising: transmitting a first message to the networkinfrastructure equipment comprising an indication of a first portion ofthe temporary identifier; and transmitting a second message, which isseparate from the first message, to the network infrastructure equipmentcomprising an indication of a second portion of the temporaryidentifier.

Paragraph 2. A method according to paragraph 1, wherein the secondmessage comprises a request for a service from a core network of thewireless telecommunications network.

Paragraph 3. A method according to paragraph 1 or paragraph 2, whereinthe first message is transmitted as part of a random access contentionresolution procedure.

Paragraph 4. A method according to any of paragraphs 1 to 3, wherein thesecond message is transmitted after the completion of a contentionresolution procedure.

Paragraph 5. A method according to any of paragraphs 1 to 4, wherein thesize of the first message is predetermined, and the size of the secondmessage is greater than the size of the first message and is notpredetermined.

Paragraph 6. A method according to any of paragraphs 1 to 5, wherein thesecond message is an RRC connection setup complete message.

Paragraph 7. A method according to any of paragraphs 1 to 6, wherein thesecond message comprises a list of one or more network sliceidentifiers, and the indication of the second portion of the temporaryidentifier comprises a network slice identifier at a predeterminedposition in the list.

Paragraph 8. A method according to paragraph 7, wherein the networkslice identifier at the predetermined position in the list is associatedwith an access and mobility management function, AMF, in a core networkof the wireless telecommunications network with which the terminaldevice has established a protocol data unit, PDU, session.

Paragraph 9. A method according to any of paragraphs 1 to 8, wherein thesecond message comprises a indication of a protocol data unit, PDU,session identity, and the indication of the second portion of thetemporary identifier comprises the indication of a protocol data unit,PDU, session identity.

Paragraph 10. A method according to any of paragraphs 1 to 6, whereinthe indication of the second portion of the temporary identifiercomprises one of a tracking area identifier, an identifier of an accessand mobility management function, AMF, in a core network of the wirelesstelecommunications network with which the terminal device is registered,and an identifier of a group of access and mobility managementfunctions, the group including the access and mobility managementfunction with which the terminal device is registered.

Paragraph 11. A method according to any of paragraphs 1 to 10, themethod comprising: transmitting a random access request message on arandom access channel to the network infrastructure equipment of thewireless telecommunications network, and receiving a random accessresponse message from the network infrastructure equipment, wherein thefirst message is transmitted in response to receiving the random accessresponse message.

Paragraph 12. A method according to any of paragraphs 1 to 11, furthercomprising the terminal device determining a size for the indication ofthe first portion of the temporary identifier based on a size of thefirst message.

Paragraph 13. A method according to any of paragraphs 1 to 12, whereinthe temporary identifier is one of a system architectureevolution-temporary mobile subscriber identity, S-TMSI, and a 5G-S-TMSI,comprising at least 48 bits.

Paragraph 14. A method of operating a network infrastructure equipmentof a wireless telecommunications network to establish a radio connectionwith a terminal device, wherein the terminal device is associated with apreviously-allocated temporary identifier that identifies the terminaldevice within the wireless telecommunications network, the methodcomprising: receiving a first message from the terminal devicecomprising an indication of a first portion of the temporary identifier;and receiving a second message, which is separate from the firstmessage, from the terminal device comprising an indication of a secondportion of the temporary identifier.

Paragraph 15. A method according to paragraph 14, wherein the firstmessage is transmitted as part of a random access contention resolutionprocedure.

Paragraph 16. A method according to paragraph 14 or paragraph 15,wherein the second message is transmitted after the completion of acontention resolution procedure.

Paragraph 17. A method according to any of paragraphs 14 to 16, whereinthe size of the first message is predetermined, and the size of thesecond message is greater than the size of the first message and is notpredetermined.

Paragraph 18. A method according to any of paragraphs 14 to 17, whereinthe second message is an RRC connection setup complete message.

Paragraph 19. A method according to any of paragraphs 14 to 18, whereinthe second message comprises a request for a service from a core networkof the wireless telecommunications network.

Paragraph 20. A method according to paragraph 19, the method comprising:determining an identity of an access and mobility management function,AMF, in the core network based on the indication of the first portion ofthe temporary identifier and the indication of the second portion of thetemporary identifier, and transmitting the request for the service tothe identified access and mobility management function.

Paragraph 21. A method according to any of paragraphs 14 to 20, whereinthe second message comprises a list of one or more network sliceidentifiers, and the indication of the second portion of the temporaryidentifier comprises a network slice identifier at a predeterminedposition in the list.

Paragraph 22. A method according to paragraph 21, wherein the networkslice identifier at the predetermined position in the list is associatedwith an access and mobility management function, AMF, in a core networkof the wireless telecommunications network with which the terminaldevice has established a protocol data unit, PDU, session.

Paragraph 23. A method according to any of paragraphs 14 to 22, whereinthe second message comprises a indication of a protocol data unit, PDU,session identity, and the indication of the second portion of thetemporary identifier comprises the indication of a protocol data unit,PDU, session identity.

Paragraph 24. A method according to any of paragraphs 14 to 20, whereinthe indication of the second portion of the temporary identifiercomprises one of a tracking area identifier, an identifier of an accessand mobility management function, AMF, in the core network with whichthe terminal device is registered, and an identifier of a group ofaccess and mobility management functions, the group including the accessand mobility management function with which the terminal device isregistered.

Paragraph 25. A method according to any of paragraphs 14 to 24, themethod comprising: receiving a random access request message transmittedby the terminal device on a random access channel, and transmitting arandom access response message in response to the random access requestmessage, wherein the first message is transmitted by the terminal devicein response to receiving the random access response message.

Paragraph 26. A method according to any of paragraphs 14 to 25, whereinthe temporary identifier is one of a system architectureevolution-temporary mobile subscriber identity, S-TMSI, and a 5G-S-TMSI,comprising at least 48 bits.

Paragraph 27. A terminal device for establishing a radio connection withnetwork infrastructure equipment in a wireless telecommunicationsnetwork, wherein the terminal device is associated with apreviously-allocated temporary identifier that identifies the terminaldevice within the wireless telecommunications network; wherein theterminal device comprises controller circuitry and transceiver circuitryconfigured such that the terminal device is operable to: transmit afirst message to the network infrastructure equipment comprising anindication of a first portion of the temporary identifier; and transmita second message, which is separate from the first message, to thenetwork infrastructure equipment comprising an indication of a secondportion of the temporary identifier.

Paragraph 28. Circuitry for a terminal device for establishing a radioconnection with network infrastructure equipment in a wirelesstelecommunications network, wherein the terminal device is associatedwith a previously-allocated temporary identifier that identifies theterminal device within the wireless telecommunications network; whereinthe circuitry comprises controller circuitry and transceiver circuitryconfigured such that the terminal device is operable to: transmit afirst message to the network infrastructure equipment comprising anindication of a first portion of the temporary identifier; and transmita second message, which is separate from the first message, to thenetwork infrastructure equipment comprising an indication of a secondportion of the temporary identifier.

Paragraph 29. A network infrastructure equipment for establishing aradio connection with a terminal device in a wireless telecommunicationsnetwork, wherein the terminal device is associated with apreviously-allocated temporary identifier that identifies the terminaldevice within the wireless telecommunications network , wherein theinfrastructure equipment comprises controller circuitry and transceivercircuitry configured such that the infrastructure equipment is operableto: receive a first message from the terminal device comprising anindication of a first portion of the temporary identifier; and receive asecond message, which is separate from the first message, from theterminal device comprising an indication of a second portion of thetemporary identifier.

Paragraph 30. Circuitry for a network infrastructure equipment forestablishing a radio connection with a terminal device in a wirelesstelecommunications network, wherein the terminal device is associatedwith a previously-allocated temporary identifier that identifies theterminal device within the wireless telecommunications network , whereinthe circuitry comprises controller circuitry and transceiver circuitryconfigured such that the infrastructure equipment is operable to:receive a first message from the terminal device comprising anindication of a first portion of the temporary identifier; and receive asecond message, which is separate from the first message, from theterminal device comprising an indication of a second portion of thetemporary identifier.

REFERENCES

[1] RP-161464, “Revised WID for Further Enhanced MTC for LTE,” Ericsson,3GPP TSG RAN Meeting #73, New Orleans, USA, Sep. 19-22, 2016

[2] RP-161901, “Revised work item proposal: Enhancements of NB-IoT”,Huawei, HiSilicon, 3GPP TSG RAN Meeting #73, New Orleans, USA, Sep.19-22, 2016

[3] RP-170732, “New WID on Even further enhanced MTC for LTE,” Ericsson,Qualcomm, 3GPP TSG RAN Meeting #75, Dubrovnik, Croatia, Mar. 6-9, 2017

[4] RP-170852, “New WID on Further NB-IoT enhancements,” Huawei,HiSilicon, Neul, 3GPP TSG RAN Meeting #75, Dubrovnik, Croatia, Mar. 6-9,2017

[5] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radioaccess”, John Wiley and Sons, 2009

1. A method of operating a terminal device to establish a radioconnection with network infrastructure equipment in a wirelesstelecommunications network, wherein the terminal device is associatedwith a previously-allocated temporary identifier that identifies theterminal device within the wireless telecommunications network; themethod comprising: transmitting a first message to the networkinfrastructure equipment comprising an indication of a first portion ofthe temporary identifier; and transmitting a second message, which isseparate from the first message, to the network infrastructure equipmentcomprising an indication of a second portion of the temporaryidentifier.
 2. A method according to claim 1, wherein the second messagecomprises a request for a service from a core network of the wirelesstelecommunications network.
 3. A method according to claim 1, whereinthe first message is transmitted as part of a random access contentionresolution procedure.
 4. A method according to claim 1, wherein thesecond message is transmitted after the completion of a contentionresolution procedure.
 5. A method according to claim 1, wherein the sizeof the first message is predetermined, and the size of the secondmessage is greater than the size of the first message and is notpredetermined.
 6. A method according to claim 1, wherein the secondmessage is an RRC connection setup complete message.
 7. A methodaccording to claim 1, wherein the second message comprises a list of oneor more network slice identifiers, and the indication of the secondportion of the temporary identifier comprises a network slice identifierat a predetermined position in the list.
 8. A method according to claim7, wherein the network slice identifier at the predetermined position inthe list is associated with an access and mobility management function,AMF, in a core network of the wireless telecommunications network withwhich the terminal device has established a protocol data unit, PDU,session.
 9. A method according to claim 1, wherein the second messagecomprises a indication of a protocol data unit, PDU, session identity,and the indication of the second portion of the temporary identifiercomprises the indication of a protocol data unit, PDU, session identity.10. A method according to claim 1, wherein the indication of the secondportion of the temporary identifier comprises one of a tracking areaidentifier, an identifier of an access and mobility management function,AMF, in a core network of the wireless telecommunications network withwhich the terminal device is registered, and an identifier of a group ofaccess and mobility management functions, the group including the accessand mobility management function with which the terminal device isregistered.
 11. A method according to claim 1, the method comprising:transmitting a random access request message on a random access channelto the network infrastructure equipment of the wirelesstelecommunications network, and receiving a random access responsemessage from the network infrastructure equipment, wherein the firstmessage is transmitted in response to receiving the random accessresponse message.
 12. A method according to claim 1, further comprisingthe terminal device determining a size for the indication of the firstportion of the temporary identifier based on a size of the firstmessage.
 13. A method according to claim 1, wherein the temporaryidentifier is one of a system architecture evolution-temporary mobilesubscriber identity, S-TMSI, and a 5G-S-TMSI, comprising at least 48bits.
 14. A method of operating a network infrastructure equipment of awireless telecommunications network to establish a radio connection witha terminal device, wherein the terminal device is associated with apreviously-allocated temporary identifier that identifies the terminaldevice within the wireless telecommunications network, the methodcomprising: receiving a first message from the terminal devicecomprising an indication of a first portion of the temporary identifier;and receiving a second message, which is separate from the firstmessage, from the terminal device comprising an indication of a secondportion of the temporary identifier.
 15. A method according to claim 14,wherein the first message is transmitted as part of a random accesscontention resolution procedure.
 16. A method according to claim 14,wherein the second message is transmitted after the completion of acontention resolution procedure.
 17. A method according to claim 14,wherein the size of the first message is predetermined, and the size ofthe second message is greater than the size of the first message and isnot predetermined.
 18. A method according to claim 14, wherein thesecond message is an RRC connection setup complete message.
 19. A methodaccording to claim 14, wherein the second message comprises a requestfor a service from a core network of the wireless telecommunicationsnetwork.
 20. A method according to claim 19, the method comprising:determining an identity of an access and mobility management function,AMF, in the core network based on the indication of the first portion ofthe temporary identifier and the indication of the second portion of thetemporary identifier, and transmitting the request for the service tothe identified access and mobility management function.
 21. A methodaccording to claim 14, wherein the second message comprises a list ofone or more network slice identifiers, and the indication of the secondportion of the temporary identifier comprises a network slice identifierat a predetermined position in the list.
 22. A method according to claim21, wherein the network slice identifier at the predetermined positionin the list is associated with an access and mobility managementfunction, AMF, in a core network of the wireless telecommunicationsnetwork with which the terminal device has established a protocol dataunit, PDU, session.
 23. A method according to claim 14, wherein thesecond message comprises a indication of a protocol data unit, PDU,session identity, and the indication of the second portion of thetemporary identifier comprises the indication of a protocol data unit,PDU, session identity.
 24. A method according to claim 14, wherein theindication of the second portion of the temporary identifier comprisesone of a tracking area identifier, an identifier of an access andmobility management function, AMF, in the core network with which theterminal device is registered, and an identifier of a group of accessand mobility management functions, the group including the access andmobility management function with which the terminal device isregistered.
 25. A method according to claim 14, the method comprising:receiving a random access request message transmitted by the terminaldevice on a random access channel, and transmitting a random accessresponse message in response to the random access request message,wherein the first message is transmitted by the terminal device inresponse to receiving the random access response message.
 26. A methodaccording to claim 14, wherein the temporary identifier is one of asystem architecture evolution-temporary mobile subscriber identity,S-TMSI, and a 5G-S-TMSI, comprising at least 48 bits.
 27. A terminaldevice for establishing a radio connection with network infrastructureequipment in a wireless telecommunications network, wherein the terminaldevice is associated with a previously-allocated temporary identifierthat identifies the terminal device within the wirelesstelecommunications network; wherein the terminal device comprisescontroller circuitry and transceiver circuitry configured such that theterminal device is operable to: transmit a first message to the networkinfrastructure equipment comprising an indication of a first portion ofthe temporary identifier; and transmit a second message, which isseparate from the first message, to the network infrastructure equipmentcomprising an indication of a second portion of the temporaryidentifier.
 28. Circuitry for a terminal device for establishing a radioconnection with network infrastructure equipment in a wirelesstelecommunications network, wherein the terminal device is associatedwith a previously-allocated temporary identifier that identifies theterminal device within the wireless telecommunications network; whereinthe circuitry comprises controller circuitry and transceiver circuitryconfigured such that the terminal device is operable to: transmit afirst message to the network infrastructure equipment comprising anindication of a first portion of the temporary identifier; and transmita second message, which is separate from the first message, to thenetwork infrastructure equipment comprising an indication of a secondportion of the temporary identifier.
 29. A network infrastructureequipment for establishing a radio connection with a terminal device ina wireless telecommunications network, wherein the terminal device isassociated with a previously-allocated temporary identifier thatidentifies the terminal device within the wireless telecommunicationsnetwork, wherein the infrastructure equipment comprises controllercircuitry and transceiver circuitry configured such that theinfrastructure equipment is operable to: receive a first message fromthe terminal device comprising an indication of a first portion of thetemporary identifier; and receive a second message, which is separatefrom the first message, from the terminal device comprising anindication of a second portion of the temporary identifier. 30.Circuitry for a network infrastructure equipment for establishing aradio connection with a terminal device in a wireless telecommunicationsnetwork, wherein the terminal device is associated with apreviously-allocated temporary identifier that identifies the terminaldevice within the wireless telecommunications network , wherein thecircuitry comprises controller circuitry and transceiver circuitryconfigured such that the infrastructure equipment is operable to:receive a first message from the terminal device comprising anindication of a first portion of the temporary identifier; and receive asecond message, which is separate from the first message, from theterminal device comprising an indication of a second portion of thetemporary identifier.